Improving Pre-Operative Flexion in Primary TKA: A Surgical Technique Emphasizing Knee Flexion with 5-Year Follow-Up

Abstract

This study prospectively reviews a consecutive series of 228 primary total knee arthroplasty (TKA) procedures utilizing a technique to optimize knee flexion. The main features include: (1)the use of a “patellar friendly” femoral component and reduced thickness patellar components, (2) patient individualized adjustment of the femoral component rotation set strictly to the anterior-posterior femoral axis, (3)a rigorous flexion compartment debridement to remove non-essential posterior femoral bone with a Z-osteotome, and (4)incorporation of a rapid recovery protocol with features to promote knee flexion. Results were categorized into three groups: low pre-op flexion (90 degrees and below), regular pre-op flexion (91-125 degrees), and high pre-op flexion (126 degrees and above). Average flexion in the low flexion group improved by 20 degrees at 6 weeks, 28 degrees at 3 months, 31 degrees at 1 year, and 30 degrees at 5 years. In the regular flexion group, average flexion improved by 2 degrees at 6 weeks, 10 degrees at 3 months, 12 degrees at 1 year, and 13 degrees at 5 years. Finally, in the high flexion group, average flexion decreased by 7 degrees at 6 weeks, regained preoperative levels at 3 months, and increased by 3 degrees at 1 year and 4 degrees at 5 years. In summary, a technique that emphasizes patellofemoral kinematics can consistently improve flexion in TKA in short and long-term follow-up.